1. Field of the Invention
The present invention relates to a three-dimensional printing apparatus, and in more detail, to a three-dimensional printing apparatus that produces a three-dimensional printing object by use of a photocurable resin that is cured by being irradiated with light.
2. Description of the Related Art
Conventionally, three-dimensional printing apparatuses that produce a three-dimensional printing object by use of a photocurable resin are known. A “photocurable resin” is a resin that has a property of being cured by being irradiated with light such as visible light, ultraviolet light or the like, and is liquid in an uncured state.
One of such three-dimensional printing apparatuses is, for example, a suspension stacking system. A three-dimensional printing apparatus of the suspension stacking system stacks, while suspending, photocurable resin layers cured to have a predetermined cross-sectional shape to perform printing. Such an apparatus produces a three-dimensional printing object in the following procedure. First, a photocurable resin in a liquid state is stored in a container including a light-transmissive plate as a bottom plate. Next, a holder that is to act as a base table for a three-dimensional printing object to be produced is located in the photocurable resin. Then, the light-transmissive plate is irradiated with light by a projector or the like. As a result, a portion of the photocurable resin, located between the holder and the light-transmissive plate, that has been irradiated with the light is cured. Thus, a cured layer is formed on a bottom surface of the holder. Next, the holder is moved upward to peel off the cured layer from the light-transmissive plate. Then, the light-transmissive plate is irradiated with light. As a result, a portion of the photocurable resin, located between the cured layer and the light-transmissive plate, that has been irradiated with light is cured. Thus, another cured layer is formed below the cured layer first formed. Then, such an operation is repeated to produce a three-dimensional printing object including a plurality of cured layers that are stacked.
The above-described three-dimensional printing apparatus of the suspension stacking system produces a three-dimensional printing object by stacking the cured layers in repetition. Therefore, in order to produce a three-dimensional printing object with high precision, the precision with which each cured layer is produced is important. The precision of the thickness of each cured layer depends on the precision of the height of a movable member (hereinafter, the height of a movable member will be referred to as the “position of the movable member”). An error in the position of the movable member causes an error in the thickness of the cured layer. The position of the movable member is determined by the height thereof from a predetermined origin position. Upward and downward movements of the movable member are controlled on the basis of the origin position.
However, with the above-described production of a three-dimensional printing object, when the cured layer is formed, the cured layer and the light-transmissive plate are in close contact with each other. Therefore, when the cured layer is peeled off from the light-transmissive plate, a load is applied to the movable member. This load may possibly deviate the origin position of the movable member. The conventional three-dimensional printing apparatus has a problem that an operator cannot check whether or not deviation from the origin position has occurred.